Luteal Phase

The luteal phase is the second half of the menstrual cycle, spanning from ovulation to the start of the next period (approximately days 14-28 in a typical cycle), during which the empty follicle transforms into the corpus luteum and produces progesterone to prepare the uterine lining for potential embryo implantation. Women with PCOS who do ovulate may experience a compromised luteal phase with insufficient progesterone production (called luteal phase defect), which can contribute to difficulty conceiving, early pregnancy loss, and cycle irregularity. Tracking basal body temperature and progesterone levels during the luteal phase helps assess whether ovulation has occurred and whether progesterone support may be needed.